Furuno FR-8251, FR-8111 manual Suppressing Second-Trace Echoes, Echo average

3)Press the ENTER/SELECT key.

4)Select ECHO AVG and press the ENTER/SE- LECT key.

5)Select 1, 2, or 3.

1:Distinguishes targets from sea clutter and suppresses brilliance of unstable echoes.

2:Distinguishes small stationary targets such as navigation buoys.

3:Displays distant targets as stable echoes.

6)Press the ENTER/SELECT key.

7)Press the MENU key.

a) Echo average OFF b) Echo average 1

Figure 1-26 Echo average

WARNING

Do not use the Echo Average feature under heavy pitching or rolling; loss of true targets may result.

Echo averaging uses scan-to-scan signal correla- tion technique based on the true motion over the ground of each target. Thus, small stationary tar- gets such as buoys will be shown while suppress- ing random echoes such as sea clutter. True echo average is not however effective for picking up small targets running at high speeds over the ground.

The echo average feature is inoperable when a heading signal is not available. If you wish to use this feature without a heading signal, system ini- tialization is required. (Consult a FURUNO rep- resentative or dealer.)

Note: Echo averaging also requires ship’s speed information from a log or manual entry.

1.31Suppressing Second-Trace Echoes

In certain situations, echoes from very distant targets may appear as false echoes (second-track echoes) on the screen. This occurs when the re- turn echo is received one transmission cycle later, namely, after a next radar pulse has been trans- mitted.

To suppress them, turn on 2ND ECHO on the ECHO SIG menu.

1)Press the MENU key.

2)Select the ECHO SIG menu.

3)Press the ENTER/SELECT key.

4)Select 2ND ECHO and press the ENTER/SE- LECT key.

5)Select ON.

6)Press the ENTER/SELECT key.

7)Press the MENU key.

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